Antiretroviral therapy (ART) has the potential to substantially reduce male HIV-1 infectivity and thereby prevent sexual transmission of HIV-1 infection, especially in sub-Saharan Africa. However, studies of male genitourinary HIV-1 shedding have been limited by difficulties with collecting semen samples by masturbation. The specific aims of this proposal are to: (1) evaluate the time course and magnitude of suppression of genitourinary and rectal mucosal HIV-1 shedding among men initiating ART; (2) to evaluate the validity of post-prostatic massage fluid/urine (post-PMF/U) as a surrogate marker of male HIV-1 infectivity in place of semen; and (3) to determine the feasibility and acceptability of two different genital sampling methods: semen collection by masturbation versus post-PMF/U in a population of HIV-1- seropositive Kenyan men. We will determine the dynamics of HIV-1 decay in genitourinary and rectal mucosal samples by prospectively following 16 men over the first month after ART initiation. We will also collect paired genitourinary specimens from 30 men to compare HIV-1 RNA levels in seminal plasma versus post-PMF/U. Finally, we will determine the feasibility and acceptability of these two different genitourinary collection methods for 30 strictly heterosexual and 30 bisexual or homosexual men. With the University of Washington's expertise in male HIV-1 infectivity, experience in conducting HIV-1 shedding studies in Kenya, and a new cohort with access to men at high risk for HIV-1 transmission, we are confident of our ability to carry out the proposed research. The results of this pilot study will enable us to plan further, more in-depth research on male infectivity to optimize patient management and public health strategies for the prevention of sexual HIV-1 transmission in sub-Saharan Africa. Transmission of HIV from men to their sexual partners is of major concern for HIV prevention efforts, especially in sub-Saharan Africa. We propose to evaluate the impact of antiretroviral therapy on the amount of HIV detected in the genital and rectal secretions of HIV-infected men. Because genital samples are difficult to collect from men, we will evaluate the validity, feasibility, and acceptability two different collection methods in heterosexual men and men who have sex with men in Kenya. [unreadable] [unreadable] [unreadable]